Preheat the oven to 375°F (190°C).
Butterfly each chicken breast by slicing horizontally to create two thinner pieces, then cut each piece into 6–8 strips.
In a shallow dish, whisk together the buttermilk and Sriracha (or cayenne) until combined.
In a second shallow dish, whisk the flour with dried thyme, cayenne pepper, seasoned salt, and ground black pepper.
Dip each chicken strip into the buttermilk mixture, then dredge in the seasoned flour, pressing to coat evenly; place coated strips on a sheet pan to rest.
Heat the canola oil in a 10- or 12-inch skillet over medium heat until shimmering and a drop of water sizzles.
Working in batches (3–5 strips per batch), fry the strips until golden brown on the first side, about 3 minutes, then flip and brown the other side, about 3 more minutes; transfer browned strips to the sheet pan.
Place the sheet pan with the browned strips into the preheated oven and bake 12–18 minutes, until the juices run clear when pierced and internal temperature reaches 165°F (74°C).
Let the chicken rest about 3 minutes before serving.